Down Memory Lane: The Los Angeles Coastal Prairie and Its
Vernal Pools

Abstract

The last major remnant of the Los Angeles Coastal Prairie was
a portion of a 300-acre site destroyed as habitat in the late
1960s. Unfortunately the unique community was lost before it
could be thoroughly studied. The substrate, which defined the
prairie, was consolidated sand of the pre-Flandrian sand dune
formation established during the Pleistocene. The prairie
covered about 36 square miles, extending north-south from the
crest of the Ballona Bluffs to Palos Verdes and inland from
the lee of the El Segundo sand dunes for three to six miles.
The area was rich with vernal pools and some marshy areas. It
was renowned for spectacular wildflower displays. The
historical plant community of the prairie is reconstructed
using herbarium records and historical sources and
illustrated using anecdotal records.

Historical Description

Lay people have long recognized the unique character of the
Los Angeles Coastal Prairie. The plains rolling to the sea
are described in many travelers' accounts of early Los
Angeles (Brewer 1930). Historian Roy Rosenberg writes of the
time before the prairie was converted from ranching to dry
farming in the 1800s by Inglewood founder Daniel Freeman:

[I]t is recorded that the Freeman children rode over the
rancho through fields of wildflowers that extended to the
Pacific. The sight of these great fields, suddenly
confronting a person as he neared the top of Baldwin Hills,
brought as enthusiastic exclamations of surprise and wonder
from his lips as does the present panorama which greets the
traveller as he speeds over ribbons of concrete enroute
from the metropolitan district to Inglewood. Where once
grew wild flowers with abandon -- poppies, lupin, mustard,
horseradish and verbena -- there now appears a sea of
lights which that great raconteur, Alexander Wolcott, has
aptly likened to "the babel of a million tungstens"
(Rosenberg 1938:12-13).

A Manhattan Beach resident wrote of his childhood in the
1920s:

While living at 3116 Alma, we almost always walked to
school. We walked over the sanddunes, through the area
where Grandview School is located, across the fields, over
the railroad tracks, past the Catholic Church property.
Quite often we would pick wild flowers like Lupins, Indian
Paint Brush, and mustard flower, which grew everywhere, to
take to our teachers (Dow 1976:27).

Although the landscape that inspired it is now largely gone,
there remains a Prairie Avenue in Inglewood.

Extent and Edaphic Conditions

Based on a map developed by Cooper (1967) for his
comprehensive review of the coastal sand dunes of California,
this map shows the extent of the prairie and its vernal
pools. The prairie was defined edaphically by pre- Flandrian
dunes, which coincide with the Oakley Sand formation shown by
the U.S. Bureau of Soils survey (Nelson 1919). The undrained
vernal pools were presumably created by coastal ridges
degraded over time. To the south, the prairie was bounded by
the Palos Verdes uplift and an extensive marsh system. To the
east the Torrance plain was characterized by sage scrub,
while the northern boundary was formed by the Ballona Bluffs.
The western edge of the prairie was the actively flowing
Flandrian sand dunes along the immediate coast. In contrast,
the sand of the earlier dune system, created during the
80,000 years prior to the last glaciation, had become more or
less consolidated, presenting the soil conditions that
defined the prairie. The enormous quantities of sand
contained in both dune systems was provided by alluvial sand
carried by Ballona Creek, which until the 1800s was fed by
the Los Angeles River.